Shockproof electromagnet with armature



Jan- 6, 1948. E. H; AYERS Er AL `SHOCKPRO0F ELECTROMAGNET WITH ARMATURE Filed Nov'. 1v, 1943 en dorf.

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...maw r ge dr.. m .E Ed T F MW Patented Jan. 6, 1948 SHOCKPBOOF ELETROMAGNET wrrn ARMATURE Edgar H. Ayers and Andrew G. Elmendorf, Schenectady, N. Y., assignors to General Electric Company, a corporation of New York Application November 17, 194s, serai No. 510,660 4 claims. (cl. ris-33s) instantaneously when it strikes the stationary part. This resilient mounting eliminates to a great extent the inherent pounding and battering between the armature and a xed pole piece.

We also provide positive means for clamping and fastening the stationary part of the magnet core to the resilient support and for fastening the armature of the magnet to the movable contact member. This is elected by clamping members having complementary curved surfaces which are clamped together by bolts so that the bolt itself must stretch in order for one part to move with respect to the other.

. Other features of vour invention are a tspecial stationary support for the stationary contacts which isadjustable slidably on the supporting base for the switch thereby to raise or lower the stationary contacts so as to adjust the full open position between the stationary and moving contacts and thereby adjust the wipe between the contacts. We also provide a simple and reliable common supporting and guiding member for supporting the coil on the stationary magnet core and guiding the armature and other moving parts of the magnet.

For a more complete understanding of our invention, reference should be had to the accompanying drawing, Fig. 1 of which is a front elevation view partly in section of a contactor embodying my invention; Fig. 2 is a viewof the device shown in Fig. 1 mainly in section .taken along the line 2--2 of Fig. 1 looking in the direction of the arrows; Fig. 3 is a fragmentary view showing details of the resilient support for the magnet; Fig. 4 is a view in perspective of the magnet with the coil removed showing the supporting and guiding parts; while Fig. 5 is a fragmentary view showing a modified form of arc chamber embodying our invention.

Referring to the drawing, in one form of our invention we provide a metal base or stationary support I0 on which is mounted by screws II and I2 a block I3 made of electrically insulating material forming a support for the stationary contacts, and on which-also is mounted on a resilient bracket' I4 an operating magnet I5.

As shown, the bracket I4 is integral with the stationary support I0 and is formed from a lanced rectangular portion of the base which is bent forward or to the right,as seen in Fig. 2, and then has its end constituted by two projections IB and I'I (Fig. l3) bent downward to form a suppoiiJ for the stationary magnet core I8. A special clamping mounting is provided between the magnet core I8 and the supporting projections I6 and Il comprising depressed portions I and 20 in their ends, these depressed portions being parts of cylindrical surfaces and having their center lines coincident and extending, as shown, transversely with respect to the bracket I4, i. e., horizontally, as seen in Figs. 1 and 2. On the upper portion or arm of the three-legged magnet core I8 secured in engagement with the projections I 6 and I'I are complementary projecting portions (not shown) which fit into the depressed portions or recesses I9 and 20 having transversely curved walls extending parallel with the plane of the bracket I4. Similar projections are provided on the opposite outer side of the magnet core, one of these projections 2I being shown. Another similar projection on this outer side is covered by a recessed concave-convex portion 22 in the armature guide and coil supporting member 23. .Clamping bolts 24 and 25 (Fig. 1) extend through the holes 26 and 2l in the magnet core and the member 23, these bolts having their ends threaded and screwed into tapped holes 28 and 29 in the projections I6 and I1.

In the complete assembly it will be observed that a second guiding and supporting member 30 (Fig. 2) identical in construction with the member 23 is provided on the inner side of the magnet core opposite the member 23. Also, it will be understood that the member 23, a fragmentary view only of which is shown in Fig. 4, has a second laterally extending recessprojection 30a on its right-hand side, as seen in Fig. 1, similar to the projection 22. The heads of the clamping bolts 24 and 25 are clamped against these recess projections 22 and 30a. Similar projections on the guide and support 30, suitably stamped or bent so as to be concave-convex, are clamped between the magnet core I8 and the supporting projections I6 and I1. Thus the relatively thin metal of the guide and support 30 is stamped so that its side adjacent the projections I6 and I1 has portions fitting into the recesses i9 and 28, and the opposite side of the guide and support 30 provide similar recesses for the projections on that side of the magnet core.

.Thus, when the upper end of the magnet core is clamped to the projections I8 and i1 by the bolts 24 and 25, the alternate recessed and projecting portions of supports 23 and 30, the magnet core and the projections IS and I1 are clamped securely to each other. It will be observed that these complementary recessed and projecting portions prevent relative movement between the parts, especially between the magnetcore and its supporting projections I6 and I1. This securing effect is dependent upon the tension of the bolts. In other words, the alternate depressed portions and complementary projecting portions provide engaging surfaces at an acute angle with a plane perpendicular to the bolts, and thus offer a wedging action with each other to prevent movement of the magnet core on the projections i and i1 in a plane at right angles with the bolts. Therefore, any such movement applies a tension to the bolts and can take place only in the event that the bolts stretch or become loose. Even then this possible relative movement is limited as compared with engaging iiat surfaces clamped together. In the latter case, relative movement between the parts having the engaging ilat surfaces is dependent upon friction between them.

The supporting bracket i4 for the magnet is appreciably flexible. In fact, the stationary support I0 is made of a metal having a thickness selected so that the support I4 lanced from it will have the desired degree of resiliency for mounting the stationary core I8. Thus when the armature 3| is picked up upon energization of the coil 32 and strikes against the stationary core I8, more particularly against the ends oi the outer arms 33 and 34 of the stationary core, while Inoving at high speed, the force of the impact is transmitted to the stationary core member which yields somewhat because of the flexibility of the support I4, This means that the moving armai ture 3| is not brought suddenly to rest against a solid unyielding member but, on the other hand, is brought, to rest gradually with gradual dissipa' tion of its kinetic energy against an inertia member constituted by the stationary core member I8 having a, resilient support I4. This gradual bringing to rest of the armature eliminates to a great extent the pounding and battering of the engaging surfaces of the armature and the stationary magnet core.

The guiding and supporting members 23 and 30 are channel-shaped, as shown in Figs. 2 and 4. As shown, the support 23 has a side 23a resting against the left-hand side of the middle leg 35 of the magnet. The other half of the member 23, which is cut away in Fig. 4, is identical and is provided with a side similar to 23a engaging the right-hand side of the middle core leg. Also, the member 23 is provided with a lanced portion 3B which extends inwardly and has its inner end resting against the front side of the middle leg, as seen in Fig. 4, whereby the front wall of the member 23 is spaced from the middle leg. The projections 22 and 30a at the upper end of the member 23 are connected to this middle portion by oiset portions. This space between the middle portion of the member 23 and the middle leg is provided "for a strap 31 forming with a similar strap 38 a mechanical connection between the armature 3| and an insulating cross member 39 carrying the movable switch contacts. The member 31 is provided with a longitudinal central slot 31a through which extends the spacing projection 35. The strap 38 and the member 30 are identical in construction with the similar parts 31 and 23. Preferably, as is shown in Fig. 4, the straps 31 and 38 are extensions oi relatively thick outside laminations of the armature 3i. These outside lamlnations 31 and 38 are made oi a suitable high conductivity material, such as brass. Two electrically conducting rivets Sla and 3Ib extend through opposite ends of the lower arm of the armature. These rivets are electrically connected to the laminations 31 and 38 and Iorm with them a closed electrically conducting pole shader loop for the two poles of the armature.

At their lower ends the members 23 and 30 are provided with supporting projections 40 and 4I engaging the lower end of the coil 32 and holding it firmly against the upper cross member of the stationary magnet core.

A rigid clamped connection is provided between the upper ends of the straps 31 and 38 and the bar 39, similar to that provided between the stationary magnet core and the supporting bracket I4. The ends of the straps are provided with curved portions 42 and 43 curved as parts of cylinders whose center lines are perpendicular to the lengths of the straps. These curved portions t into complementary depressions in the insulating cross member 39, the cross member being clamped between the ends of the straps by means of two bolts 44 extending through them.

As shown in the drawing. the support i3, made of insulating material on which is mounted the stationary contacts, is provided with alternate high and low supporting projections. Thus, as shown, this support has three low projections 45, 46 and 41, and three high projections 48, 48 and 50. As shown clearly in Fig. 2, on these projections are secured by screws 5I electrically conducting straps carrying stationary contacts. Fig. 2 shows two straps 52 and 53 mounted on the high and low projections 49 and 46 carrying a pair of stationary contacts 54 and 55 with which cooperates a movable electrically conducting bridging member 58 mounted on the insulating cross member 39. The stationary contacts 54 and 55 are secured to the straps 52 and 53 in opposing offset relation as seen in Fig. 2. The lower end of the strap 53 is bent toward the left-hand while the lower end of the strap 52 is bent toward the right-hand, these ends being oiset as indicated. This gives the desired spacing between the stationary contacts.

Moreover, each stationary contact is enclosed in a cup-shaped member 51 made of a suitable molded electrically insulating material such as an asbestos compound, which cup forms an arc chamber. Thus, as shown, the inverted bottom, i. e., upper, wall of the member 51 is in engagement with the strap 52 with the stationary contact 54 against the lower face of this wall. These parts are mechanically secured together by a suitable rivet 58 which also forms an electrical connection between the strap 52 and the stationary contact. The cup 51 has a rectangular notch 51a in its inner side wall into which the bridging member 56 moves when the bridging member is raised to its closed circuit position with contacts on its ends in engagement with the stationary contacts. As shown, the cup 54 is identical in construction with the cup 53, as well as the cups for the other stationary contacts.

- As shown. the bridging member BB extends through a rectangular supporting member or strap 59 having its lower end secured directly to the cross member 39. A helical spring 59a in this member 59 presses the bridging contact upward against the upper end of the member, but yields 'after engagement of the contacts to provide for additional movement of the cross member 39 and the armature to their fully attracted positions. It will also be understood, as shown in Fig. 1, that the stationary contacts of a pair are offset toward each other inl directions parallel'with the drawing so that they lie on a plane perpendicular with' the drawing. It will be understood that the other two pairs of stationary and movable contacts are identical in construction with the pair described, and consequently a description of the other two pairs is thought unnecessary. The ends of the straps 52 and 53 are provided with electric connection screws 60 and 6I to which thelends of external wiring conductors may be secured thereby to connect the switch in an electric circuit.

Another feature of our invention is the provision of oblong apertures in the supporting block I3 for the screws I l and I2 which secure the block to the stationary support III. Each hole 62, as

shown in dotted lines in Fig.'2, is elongated in a vertical direction, as seen in the drawing. so that by loosening the screws the block can be adjustedy appreciably in a vertical direction. Sufficient adjustment is provided in this manner to take up a very considerable amount of wear between the contacts. In other words, as the contacts wear, the supporting block I3 can be lowered so as to lower the stationary contacts and maintain a desired predetermined gap between the contacts in the open circuit position. Also this adjustment isused to obtain an initial desired air gap.

In the modiiied form of arc chamber shown in Fig. 5, the movable contact 65 is mounted on the end of a cylindrical electrically conducting support 66. The cylindrical arc chamber cup Bil,A made of an electrically insulating, heat refractory material, has sidewalls which are substantially coextensive with the length of the support 66, the stationary contact 69 being mounted on the bottom. On the support E6 in spaced relation with the contact 65 is a ring 61 made of an electrically conducting material. This ring 6l and also the contact 65 serves as a barrier to restrict the flow of gases out of the arc cup when the contacts are being separated in the opening of an electric circuit with consequent arcing between the contacts. The ring does not fit tightly in the cylindrical bore of the cup but serves to restrict the flow of gases to such an extent that the extinguishment of the arc between the contacts is expedited. It will be understood that a support 66 is mounted on each end of an electrically conducting bridging member 89a which may be straight and which is mounted in place of the bridging member 56 of Figs. 1 and 2.

Also, in the form of Fig. 5, an iron or steel ring 'I0 is provided on the inside ofthe arc cup adjacent the bottom. Preferably, this ring is molded into the side wall of the arcing cup with its inner surface flush with the inner surface of the cup. T he stationary contact 69 is somewhat smaller in diameter than the ring and, consequently, is spaced from the ring around its periphery. This ring 'i0 is provided as a protection for the inner wall of the cup, the arc striking to the ring upon the separation of the contacts.v The ring does not erode as rapidly as the molded insulating material of the cup 6 l \\ls/`? and thereiore gives longer life for the cup. l

While we have shown particular embodiments of our invention, it will be understood ofcourse that we do not wish to be limited thereto since many modiilcations may be made, and we therefore contemplate 'by the appended claims to cover any such modincatlons as fall within the true spirit and scope of our invention.

j What we claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. An electromagnetic operator comprising a stationary support, a bracket member secured to said support and projecting from said support. a projection portion on the end of said bracket v member extending substantially parallel with said support, lsaid projection portion being provided with a recess, a stationary magnet core provided with a projection ntting into said recess, a clamping bolt extending through said magnet core and bracket member for securing said magnet core on said bracket member. a coil on said magnet core, and anarmature for said magnet core movable in a direction substantially transverse to said recess.

2. An electromagnetic operator comprising a stationary support, a resilient metal bracket member secured to said support and projecting from said support substantially at right angles thereto, projection portions on the end of said bracket member extending substantially parallel with said support, said projections each being provided with a recess having transversely curved walls extending substantially parallel with the plane of said bracket, a stationary magnet core provided with projections fitting into said recesses, clamping bolts extending through said projections and ing member made of electrically insulating material provided with recesses on opposite sides of said cross member and extending parallel with thelength thereof, said 'recesses having transversely curved walls, two straps 4extending substantially at right angles to said recesses connecting said armature with said cross member, said straps being provided with projections having transversely convex surfaces fitting into said recesses on said cross member, and means for clamping said projections in said recesses.

4. An electromagnetic operator comprising a stationary support, a bracket member secured to said support and projecting from said support, an E-shaped 4stationary magnet core, an armature for said magnet core, a pair of straps on opposite sides of the central leg of said magnet core each secured at one end to said armature and each of said straps being provided with a longitudinal -m slot, a spacing and guide member on each side of said central leg having a spacing projection extending kthrough the slot in its said strap into engagement with said central leg, a coil on said central leg surrounding said spacing members.

projections on said spacing members for securing said coil in place. and means for clamping said magnet core and said spacing members to said bracket member.

The following references are of record in the EDGAR H. AYE'RS. ANDREW G. ELMENDORF.

REFERENCES CITED me of this patent:

UNITED STATES PATENTS Number Name Date Anderson June 19, 1930 Number Van Valkenburg et al: Oct. 17, 1944 Ayers Oct. 31, 1944 

